Due to the high melting temperature and high brittleness, how to mitigate the formation of pores and cracking is still the primary issue in laser manufacturing tungsten components. A novel of strategy of using fine-sized powder was proposed in this study. Two types of pure tungsten powder, with particle size range of 18.3-63.4 μm, 3.5-28.1 μm, respectively, were used to comparatively study the printability in laser powder bed fusion. A highly dense tungsten bulk sample with relative density higher than 99%was successfully manufactured within the latter fine-sized powder. Grid samples were also fabricated with the same processing strategy. The surface and cross-sectional morphology of the as-printed samples were observed to characterize the laser scan tracks, inter-layer and defect structures. Fairly low density of surface cracks was observed on surface. The results show that the fine-sized powder enhances the printability by stabilizing melt pool. This can also be verified by finite element analysis of the temperature distribution and several micron-sized melt pool. The surface cracks have been fully removed in the grid samples. The results provide a processing strategy for further manufacturing of tungsten grid structure and industrial applications.
Qin et al. (Fri,) studied this question.